Protecting assets, continuing reliability

December 9, 2013

Power for Progress…
A weekly column from the Grand River Dam Authority

Contractors work to remove some of the loose rock on the bluff west of the Pensacola Dam powerhouse. The work is a part of a larger project to combat some of the weathering that has taken place over the years.

Maybe you have driven across historic Pensacola Dam in recent weeks and have taken notice of all the unusual activity on the bluff west of the powerhouse. After all it’s not every day you see workers hanging from the rocky face of the bluff, scaling it like mountain climbers.

In this case though, the goal reaches beyond just rock climbing. These men are actually working to alter the shape of the rocky face, removing the loose portions and overhangs and then stabilizing the rest. It’s all part of a project that the Grand River Dam Authority has been planning for quite some time, with work finally getting underway in early fall and expected to last until March 2014.

According to GRDA Chief Hydro Engineer Steve Jacoby, the effort is to combat the weathering wear and tear that has taken place over the years on a bluff that has overlooked the powerhouse of Oklahoma’s first hydroelectric facility since 1940.

“The work is being done to aid against problems with long-term weathering,” said Jacoby, explaining that many years of moisture, freezing and thawing causes some rock to crack and, eventually, fall off. While that is not a concern to the structural integrity of the dam (it undergoes thorough inspections on a routine basis), the falling rock can be a safety hazard and could potentially cause damage to the penstocks located below the bluff.

GRDA’s solution? The first phase is to gauge the current effects of past weathering by measuring the amount of loose rock on the bluff and the amount that has chipped away and fallen over the years. Next was the actual clean up of the loose debris still hanging on the bluff in order to give the facing a reasonably smooth surface. Ground debris was also removed.

After that, “rock bolts” and reinforced fiberglass mesh will be installed across the area to prevent any rock from falling off the bluff in the future. Though the weathering cannot be prevented, this work will help slow the effects of that weathering for many years to come because, even as the rock breaks loose from the facing, the mesh and bolts will keep in on the bluff.

“[The mesh] should hold the rocks in place as they tend to weather out,” said Jacoby, “and this should be a long-term design for the next 50 years.”

So even though it might look like an extreme outdoor activity, it is really an important project being conducted to help GRDA protect important assets. In turn, that will help the utility continue its role as Oklahoma’s low-cost, reliable electricity supplier.

Headquartered in Vinita, GRDA is Oklahoma’s state-owned electric utility; fully funded by revenues from electric and water sales instead of taxes. Directly or indirectly, GRDA’s low-cost, reliable; electricity serves nearly 500,000 homes in Oklahoma and stretches into 75 of 77 counties in the state. At no cost to Oklahoma taxpayers, GRDA also manages 70,000 surface acres of lakes in the state, including Grand Lake, Lake Hudson and the W.R. Holway Reservoir. Today, GRDA’s 500 employees continue to produce the same “power for progress” that has benefited the state for 75-plus years.